Patent GB-1021813-A (GB)
Title: Improvements in or relating to change-speed gearboxes for motor vehicles
IPC: F16H61/02
Filed: 1962-12-10
Abstract: 1,021,813. Change-speed gear and control; clutch combinations. ZAHNRADFABRIK FRIEDRICHSHAFEN A.G. Dec. 10, 1962 [Dec. 8, 1961], No. 46576/62. Headings F2C and F2D. In a change-speed gear of the kind wherein an hydraulic torque converter T and a parallel bridging clutch K 1  precedes a change-speed planetary gear having ratio establishing friction clutches and/or brakes K 2 ; B 1  . . - B 5 , the contact surfaces of the clutches and/or brakes are so dimensioned that for a ratio shift under full load the amount of heat produced is not greater than 0.005 K cal./cm.<SP>2</SP> of said surfaces per gear change. Gear arrangement.-As shown, a planetary change.speed gear providing three forward reduced ratios, direct drive and two reverse ratios comprises three sun-ring trains P 1 , P 2 , P 3  and an overlapping reverse train P 4 , the former trains P 1 , P 2 , P 3  having sun gears S 1 , S 2 , S 3  fast with an intermediate shaft 4 which is driven from an input shaft 1 through the torque converter T as bridging clutch K 1  and reaction ring gears A 1 , A 2 , A 3  selectively held by brakes B 1 , B 2 , B 3 . The planet carriers ST 1 , ST 2  are respectively fast with the ring gears A 2 , A 3  and the planet carrier ST 3  is fast with an output shaft 8. On application of the brake B 3  the train P 3  acts alone for low ratio, applying the brake B 2  compounds the trains P 2 , P 3  for second ratio and applying the brake B 1  compounds all three trains for third ratio whilst a clutch K 2  between the carrier ST 1  and intermediate shaft 4 is engaged for direct drive. The reverse train comprises output carrier stepped planets P 4 , P 5  meshing reaction rings A 4 , A 5  which may be held by brakes B 4 , B 5  and a sun gear S 4  fast with the ring gear A 3 . Respective application of the brakes B 4 , B 5  compounds the reverse and third trains for low and high reverse ratios. In Fig. 2 (not shown) the above reverse train is replaced by a sun-ring forward-reverse train in series with the other three sun-ring trains, the planet carriers of the third train being connected to the sun gear of the forward-reverse train. For forward ratios the sun gear is clutched to an output ring gear whilst for reverse the planet carrier is held by a brake. Clutches and brakes.-As shown, all the clutches and brakes are hydraulically operated and are cooled by lubricating and cooling oil supplied through ducts 60, 61. In Fig. 2 (not shown) the bridging clutch is centrifugally controlled and arranged within the torque converter core. Control.-Pressure fluid from a pump 29 is selectively supplied to the ratio establishing brakes B 1  - . - B 5  through solenoid operated valves V 1  . - V 5  and to the bridging clutch K 1  through a solenoid-operated valve 31. At commencement of ratio shift a solenoid 33 of the valve 31 is energized and moves down against a return spring 36 a valve spool 32a whereupona chamber 46 is vented at 35 and permits a spring 41 to move up a second valve spool 40 to vent the clutch line 42 at 43. On completion of ratio shift the solenoid 33 is de-energized and the valve spool 32a returned to its uppermost position wherein it blocks the vent 35 and supplies pressure fluid from a line 34 to a duct 44 connected through a throttling orifice 47 to the chamber 46 in which pressure slowly builds up and thus slowly moves down the valve spool 40 and a land 40b thereon to interconnect the duct 44 and clutch line 42. The bridging clutch K 1  is thereby re-engaged slowly. In Fig. 3 (not shown), wherein ratio establishing switches 51 are operated by a gear shift lever 50, the circuit to the bridging clutch control valve 54 is broken during ratio shift by energizing a relay 53 through contacts R. On establishment of a new ratio and opening of one set of contacts R the engagement of the bridging clutch is delayed for a predetermined time by a condenser 52 in parallel with the relay 53.